Pecan growers can turn to on-line resource to manage pests

Pecan growers can now use a new Web site to predict insect pest activity in their orchards and track activity across the state, said entomologists with the Texas AgriLife Extension Service.

AgriLife Extension entomologists have developed the PNCforecast System, an on-line model that uses pheromone traps and temperature to predict when pecan nut casebearers will be active in pecan orchards in the spring, said Dr. Allen Knutson, an entomologist with the Texas AgriLife Research and Extension Center at Dallas.

The pecan nut casebearer, or PNC, is the most damaging pest attacking pecans in Texas, Knutson said. A single, well-timed insecticide application in the spring is usually sufficient to prevent crop loss. However, knowing when to make this application is the challenge.

The PNCforecast system helps growers anticipate the appearance of this annual pest and plan management activities, he said. The system uses the pheromone traps to determine when the first pecan nut casebearers begin to fly.

The PNCforecast system then uses that “first moth” date and historic weather data for the local site to predict when casebearer moths will be depositing eggs in the orchard and when larvae will begin to tunnel into nutlets.

“Knowing these time periods is critical to managing this pest,” Knutson said. “Based upon the PNCforecast output, we know when to begin scouting the orchard to determine if casebearer infestations exceed the threshold.”

An insecticide treatment, if needed, should be most effective if applied just prior to the date when the first larvae begin tunneling into the nutlets, he said. The PNCforecast System predicts this date, helping pecan growers plan.

“However, remember that the PNCforecasts are only forecasts,” said Dr. Mark Muegge, an AgriLife Extension entomologist at Ft. Stockton. “Growers must base management decisions on actual assessment of casebearer infestations as determined by orchard scouting.”

Knutson and Muegge developed the PNCforecast System based on field data collected over 10 years from orchards in north central and west Texas, they said.

To use the PNCforecast system, growers need to know when casebearer moths are first captured in their orchards, the entomologists said. The growers also need access to historic temperature data for their locations to make predictions. Many growers monitor traps, but access to temperature data and the PNCforecast model was a challenge.

“To make the PNCforecast system accessible, we developed a Web site that allows pecan growers to enter their own trap data, then select from a menu the weather station data nearest their orchard,” Knutson said.

Once this information in entered, the PNCforecast model generates a forecast unique to that orchard, he said.

“Currently, the Web site has weather data from over 50 locations in Texas,” said Robin Williams, Web designer with the Texas A&M University department of entomology.

Williams and Dr. John Jackman, an AgriLife Extension entomologist in College Station, worked with Knutson and Muegge to develop the PNCforecast model and Web site.

“Because the PNCforecast system uses the moth capture date and local temperatures, the results have proven more accurate than previous methods,” Muegge said.

“Also, pecan growers can update their PNCforecasts one to two weeks later by inputting actual high and low daily temperatures. This further increases the accuracy of the forecast.”

Pecan growers can also see pecan nut casebearer activity reported from other orchards in Texas and Oklahoma. These forecasts are based upon data collected by county agents and entomologists with AgriLife Extension and the Oklahoma Cooperative Extension Service, Master Gardeners and volunteer pecan growers working with Extension.